The present invention relates to a process for the production of rigid closed-cell foams containing urethane, urea and biuret groups which are useful as insulating materials.
Rigid foams containing urethane and predominantly isocyanurate groups (hereinafter referred to in short as PIR o foams) have been known for some time. Trichlorofluoromethane or other halogenated hydrocarbons are normally used as blowing agents in their production.
Alkali carboxylates generally dissolved in polyols having a high OH value are typically used as catalysts in the production of these foams. Where relatively large quantities of these catalysts are used in the production of foams, the index is shifted to such an extent that the property level of the foams is adversely affected. In particular, the dimensional stability of the products is seriously impaired.